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Getting Your Data Home from CTIO (1Jun95) (from CTIO, NOAO Newsletter No. 42, June 1995) The following provides up to date information on the methods available for transport of bulk data from CTIO to observers' home institutions. Optical CCD or IR images can be written in either FITS or TAR format on any of the following media: Nine-Track Magnetic Tapes Tape transports (6250/1600 BPI) are available at each telescope (except the Schmidt) and in the La Serena computer center. Schmidt observers can access the drives at one of the other telescopes (the 1-m is recommended) over the network. Exabyte (8mm video tapes) Exabyte drives are available at each telescope (two are available in the 4-m building) and in the La Serena computer center. These are a mixture of low density (8200) and dual density (8500) devices. Thus low density tapes may be written using the local drive at any location. High density tapes can be written, but at some telescopes this involves network access of a remote drive. Many of the problems of reliability that users have encountered with Exabyte tapes can be attributed to the use of the cheaper "video grade" rather than "computer grade" tapes. Tapes supplied by CTIO (see below) are computer grade. We strongly recommend that visitors select this type if bringing their own tapes. DAT (4mm digital audio tapes) DAT drives have been installed at each telescope, and one is also available for public use in La Serena. These are SUN/HP DATs, which can write in both "standard" and compressed mode. However, users are warned that compression algorithms differ from vendor to vendor, so that compressed-format tapes will only be readable on drives of compatible type. We also have some older Wang DATs on machines in La Serena that may be used to read compressed tapes written on such drives should this be necessary. We also note that the software driver we use writes tapes with variable block sizes. Some users have encountered problems reading our DAT tapes because the software at their home institutions could not handle variable block sizes. We remind observers, especially those working with our larger CCDs, that it can take a long time to get all data written to tape. We urge users to begin the process early in their run and not leave everything to the last moment. We can supply nine-track, Exabyte and DAT tapes, but you will be charged for all tapes you take away with you as follows: Nine-Track: 600 foot $13 1200 foot $18 2400 foot $21 Exabyte: $25 DAT: $25 These prices are relatively high because we must cover the costs of shipping and handling. Consequently, you may find it more economical to bring your own media---especially Exabytes and DATs. Optical photometry data taken with the PC-ASCAP are usually written to floppy disk (both 5 1/4 and 3.5 inch disks are supported). Please bring your own floppies if you plan to take your data away in this form. In an emergency, we can usually give you an extra disk, but we do not maintain a stock of floppies on the mountain for this purpose. Alternatively, photometry data can be transferred to one of our Sun computers and thence written to tape or sent home electronically. An alternative means of getting your data home is to send it over our satellite link using ftp. However, the limited bandwidth (56 Kbaud) of the link means that this technique is only suitable for transferring limited amounts of data. By all means use it to send your single channel photometry data, small format IR images, or a few optical CCD images in order to provide rapid feedback to your collaborators back home. Do not expect to be able to ship back a whole run's worth of Tek2048 images, however. Steve Heathcote(sheathcote@noao.edu), Dan Smith (dsmith@noao.edu)
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